Electric discharge tube



G. SEIBT ELECTRIC DISCHARGE TUBE DeC. 18, 1928.

, Original Filed Aug. 26. 1921 2 Shuts-Sheet l l llllllllllllll l Dec.18, 1928.

G. SEIBT ELECTRIC DISCHARGE TUBE Original Filed Aug. 26. 1921 2Sheets-Sheet 2 Patented Dec. 18, 1928.

UNITED STATES PATENT OFFICE.

GEORG SEIBT, OF BERLIN-SCHONEBERG, GERMANY.

ELECTRIC DISCHARGE TUBE.

. Original application filed August 26, 1921, Serial No. 495,504, and inGermany October 24, 1913. Divided and this application filed September25, 1924. Serial No. 789,882.

This invention relates to electric discharge tubes or thermionic tubesfor detecting, ainplit'ying or generating alternating currents, the saidtubes being of the kind comprising a heated filament acting as a cathodewhich emits electrons, an anode to which a positive potential isimparted by its being connected to the positive pole of a local sourceof direct current and on which the electrons emitted by the cathodeimpinge, and a controlling electrode or grid to which the currents to becontrolled are applied and which under the in- I fluence of the lattercurrents varies the flow of the electrons from the cathode to the anode.

According to the invention forming the subject matter of the .presentapplication, which is a division of my application Serial No. 495,504,filed August 26, 1921, both the anode and the grid of an electricdischarge tube of the, lrind above referred to are constructed in such amanner that the entire stream of electrons passing from the cathode andradiating in all directions is utilized. This is attained by surroundinga heated cathode by a grid and placing an anode around the said grid,the latter being so constructed as to allow the stream of electrons topass all round from the cathode to the anode. It is to be understoodthat throughout this specification the word grid is intended to cover acontrolling electrode to which the currents to be controlled are appliedand which allows a stream of electrons to pass through it, and the termanode to cover an electrode which is always connected to the positivepole of a local source of direct current so as to receive a positivepotential.

Referring to the drawings in which like parts are similarly designated:

Figure 1 is a perspective view of one form of my invention;

Figure 2 is a cross section thereof;

Figure 3 is a modification of Fig. 1, with parts broken away.

In Fig. 1 I have shown an evacuated glass tube 6 containing a stretchedfilament F capable of being heated by a battery A and in lieu of a flatgrid, I have shown a cylindrical grid G G surrounding the filament F andin lieu of a flat metal plate I have shown a cylindrical metal plate Msurrounding the grid G G This gives the advantage that the entire streamof electrons passing from the heated body or filament F and radiating inall directions is utilized. The grid or inner tube consists of twosystems or sets of metal strips G1 and G the strips of one setalternating with those of the other set, insulated from one another andforming a cylinder. The anode or outer tube M is a metal cylinderslotted axially. v,

The connections and method of operation are as follows:

The filament F is heated by a small battery A. The filament emitselectrons which traverse the cylindrical grid G G before reaching theouter tubes or anode M. T is a telephone, J a galvanometer and H anauxiliary battery, the positive pole of which is connected. to the anodeM. The wires a, I) connected to the grid G G lead to the circuit whoseoscillation is to be detected or amplified. The outer tube M has in itslots which correspond to the spaces between the two combs G, and G Inconsidering the action of the construction shown in Figs. 1 and 2 I mustdistinguish between the case in which the spaces between the two sets ofstrips or combs G and Gr are opposite the slots in the tube M and thecase in which they are opposite the strips of the tube M.

In the first caseon excitation of the combs G, and G the stream ofelectrons which reaches the tube M decreases and in the second case itincreases. It is in general better to work with a decrease of the streamof electrons. The sensitiveness of the arrangement can under somecircumstances be considerably increased if an auxiliary potential isapplied to the combs Gr and G In Fig. 3 I have shown a modification.Between the filament F and the outer metallic cylindrical tube III whichacts as anode are arranged two concentric grids I and II insulated fromone another. At the one of the two grids, the grid I, is applied anauxiliary potential. The potential is produced by the element B and maybe varied by means of a contact sliding on a resistance. The auxiliarypotential may also be applied at the grid II in lieu of the grid I. Itis also pos sible to apply the auxiliary potential at both grids. In theexample shown in Fig. 3 the alternating current to be detected oramplified is applied atthe grid II. The high frequency current passing acoil W is e. g. induced to the oscillating circuit S connected to thegrid-H. A is the battery for heating the filament F, H the anodebattery, T the telephone and I a galvanometer.

5 I cl aim 1. A thermionic tube having a heatable cathode capable ofemitting a stream of electrons, a plurality of perforated gridssurrounding the said cathode and capable of allowing the stream ofelectrons to pass through them in substantially all radial directionsand of controlling it, and an anode surrounding the said grids for thepurpose of utilizing the entire stream of electrons emitted by thecathode in all radial directions.

2. A thermionic tube having a heat-able cathode capable of emitting astream of electrons, two concentric cylindrical grids surrounding thesaid cathode having openings to allow the stream of electrons to passthrough them in substantially all radial directions,

4. An electron discharge device having an electron emitting cathode, acontrol electrode. an anode, and a cylindrical electrode made up ofconducting slats said electrode being interposed between said cathodeand said anode.

In testimony that I claim the foregoing as my invention, I have signedmy name hereto.

GEORG SEIBT.

CERTIFICATE OF CORRECTION.

Patent No. 1, 696, 103.

Granted December 18, 1928, to

GEORG SEIBT.

it is hereby certified that error appears in the above numbered patentrequiring correction as follows: 6, insert "Granted under the In theheading to the printed specification after line Provisions of the Act ofMarch 3, 1921, 41 Stat. L.,

1313."; and that the said Letters Patent should be read with thiscorrection therein that the same may conform to the record of the casein the Patent Office.

Signed and sealed this 15th day of December, A. D. 1931.

(Seal) M. J. Moore, Acting Commissioner of Patents.

